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Visually Based Characterization of the Incipient Particle Motion in Regular Substrates: From Laminar to Turbulent Conditions
Published on: February 22, 2018
Edge states intermediate between laminar and turbulent dynamics in pipe flow
Tobias M Schneider1, Bruno Eckhardt
1Fachbereich Physik, Philipps-Universität Marburg, Marburg, Germany.
Summary
Researchers identified invariant edge states between laminar and turbulent pipe flow. These states, characterized by vortices and chaos, become more distinct with higher Reynolds numbers, even observable in experiments at Re=1900.
Area of Science:
- Fluid dynamics
- Nonlinear dynamics
- Chaos theory
Background:
- The transition between laminar and turbulent flow is a fundamental problem in fluid dynamics.
- Invariant states near the laminar-turbulent boundary are crucial for understanding flow dynamics.
- Controlling flow dynamics through specific quantities offers a pathway to probe these states.
Purpose of the Study:
- To investigate the dynamics near the boundary between laminar and turbulent flow in pipe systems.
- To identify and characterize invariant dynamical states at this boundary.
- To explore the influence of Reynolds number on the separation between edge states and turbulence.
Main Methods:
- Analysis of pipe flow dynamics near the laminar-turbulent transition.
- Control of flow dynamics by manipulating energy content.
- Characterization of edge states through their dynamical properties, including vortex structures and chaotic behavior.
Main Results:
- Invariant dynamical states were found to exist at the boundary between laminar and turbulent flow.
- These edge states are attracting when dynamics are confined to the boundary.
- The identified edge state is characterized by two downstream vortices and exhibits intrinsic chaotic dynamics.
- An increasing Reynolds number leads to a greater separation between the edge state and fully turbulent flow.
- These phenomena were observable down to a Reynolds number of 1900, where turbulent lifetimes are short.
Conclusions:
- The study successfully identified and characterized invariant edge states in pipe flow.
- These states play a critical role in the dynamics near the laminar-turbulent boundary.
- The findings provide insights into the complex interplay between order and chaos in fluid systems and have implications for experimental observations.
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